This attempts to help answer the question, which
files should I backup and how ?

The answer is different for most people as each have
their own tolerance to risk and loss of data. There is a scale of
activity - at one end of the scale, the vast majority of people do not
take backups at all, this incurs no time, inconvenience or immediate
expense and keeps data recovery technicians in business. At the
other end of the scale, by example, when I was responsible for the
databases on which the Yellow Page directories of the East coast of
America were based, I had to be able to recover several terabytes of data
in a very short time, so I took three independent types of backup (logical,
physical, image), on different media each day, and these were sent off
site to a fire and bomb proof safe.

What to copy. Typically it is only
necessary to backup files which are not already held elsewhere. So
as long as the installation disks, product keys and personalised settings
for an application are available there is no need to take copies of that
application. Data files, however, should be backed up as often as
the maximum amount of time the owner can bear loss of the data. So
the more frequently data is changed, and the more important the data, the
more frequently it should be backed up. There is a separate page
explaining how to back up Outlook
Express files.

Disaster recovery tests. There is little
point in backing up data unless it is recoverable in the event of loss or
corruption, so periodically it is worth proving that the data can be
brought back and used in the application. This is especially true
after the application has been updated, or hardware upgraded.

The medium used to contain the backed up data
should be different from the original source if possible as sometimes the
entire disk goes bad. Fire, flood or theft will not affect
data held well enough away from the computer.

·At about £35 for a 20GB hard disk, a second drive is often
the easiest way to provide an alternate location and, if fitted
internally, it can double up as space for temporary storage to improve
overall performance. Smaller 2.5inch external disks can often be
powered from the USB port and are a compromise between the speed and price
of the larger 3.5inch disks and the following smaller media.

·If several computers need to be backed up an external (Zip,
Jazz etc) disk may be practical. USB pen/thumb drives are popular
and commonly hold 4GB or 8GB now. They are small and convenient but not
suitable for large media collections.

·If two or more computers are connected in a local area
network then another computer may house copies.

·There are Internet sites (such as
RBack) which hold
backups for a fee - this is usually secure but you need to be sure of access in the
event of a disaster. There are also free options
as mentioned on my Blog.

·DVD drives are common now, and data greater than 4.7GB
(9.4GB if dual layer) can
be spanned over multiple disks. BluRay disks will hold 25GB per
layer but the cost is high.

Which program to use for backup. The
application used to backup data must be available at recovery time i.e.
held somewhere other than the hard disk it will be used to recover from ! Microsoft’s Backup program
is universally available, free and good for all but the most demanding
users. Failing that, third party solutions are available which offer
more bells, whistles and expense. Personally, I use Acronis
True Image for my weekly and monthly backups, and for the
really important and frequently changing files, I run Microsoft's
SyncToy to echo changes to a second internal disk on a 24
hourly schedule.

The simplest way to copy data is
the COPY command; however it does not compress data, and so is often only
suitable for already compressed files (.JPG, .MP3, .WMA, .ZIP etc.)
Programs designed for file bundling are often a good compromise between
cost and ease of use - WinZIP and RAR are the most popular.

Types of backup.

All files have
attributes, and one attribute is designed to flag whether the file has
been modified since it was last backed up. In Windows this can be
seen by adding the attributes column in Windows Explorer (right click the
column title), or in the file properties, (Advanced… button in XP).
If the Archive bit is set (i.e. visible as an ‘A’) then the file has not
been backed up since last modification. This can be used to
determine which files qualify for backup so as to avoid wasting time and
space backing up files more than once.

·Normal (partial or full). Backs up all selected
files and clears the archive bit for each file, indicating that the file
has been backed up. Normal backups give you the ability to restore
files quickly because files on the last destination medium are the most
current.

·Copy. Copies all selected files but does not
clear the archive bit for each file, indicating that the file has not been
backed up. Copying is useful if you want to back up files on a
different backup medium between
normal and incremental backups, because copying will not invalidate these
other backup operations.

·Differential. Backs up those files created or
changed since the last normal (or incremental) backup. It does not
clear the archive bit for each file, indicating that the file has not been
backed up.

·Incremental. Backs up only those files created
or changed since the last normal (or incremental) backup. It clears
the archive bit for each file, indicating that the file has been backed
up.

·Daily. Backs up all selected files that have
been modified the day the daily backup is performed.

Windows XP. Microsoft do not include the
Backup program by default in XP Home Edition, but it is available for
installation. Locate the installation CD and right click on
<your CD drive>:\VALUEADD\MSFT\NTBACKUP\NTBACKUP.MSI
Then pick the Install option. Backup will appear under the
System Tools | Accessories menu. Note however that Automated System Recovery is
only of use to XP Professional users, in the Home edition the
functionality appears to work, but there is no way to restore using it !
Also, it will not backup directly to a CD device, you have to go via a
disk file.

Boot Disk. Finally, remember to have a
means to start the computer if the hard disk fails due to hardware
problem, software corruption or virus attack. Enable System Restore,
backup WMP licences and privacy keys, create a password backup file and
keep 1ComputerCare’s number stuck underneath the keyboard. An image
backup can be included in the fixed price maintenance service
performed by 1ComputerCare. Remember: bad stuff does happen, and not
just to other people !

Sooner or later your computer will fail. It will happen at the most
inconvenient time. Take adequate precautions now.